feat(trie): add trie_nodes_batch API to TrieNodeProvider trait

Adds batch node fetching capability to reduce O(n²) proof walks when
revealing multiple blinded nodes. Default implementation falls back to
sequential fetching.

Amp-Thread-ID: https://ampcode.com/threads/T-019bfe25-43f3-75ac-98f7-32bf937b69e1
Co-authored-by: Amp <amp@ampcode.com>

crates/trie/sparse/src/provider.rs

@@ -1,6 +1,6 @@
 //! Traits and default implementations related to retrieval of blinded trie nodes.
 
-use alloy_primitives::{Bytes, B256};
+use alloy_primitives::{map::HashMap, Bytes, B256};
 use reth_execution_errors::SparseTrieError;
 use reth_trie_common::{Nibbles, TrieMask};
 
@@ -35,6 +35,23 @@ pub struct RevealedNode {
 pub trait TrieNodeProvider {
     /// Retrieve trie node by path.
     fn trie_node(&self, path: &Nibbles) -> Result<Option<RevealedNode>, SparseTrieError>;
+
+    /// Batch retrieve trie nodes by paths.
+    ///
+    /// Returns a map from path to revealed node. Missing nodes are omitted.
+    /// Default implementation falls back to sequential fetching.
+    fn trie_nodes_batch(
+        &self,
+        paths: &[Nibbles],
+    ) -> Result<HashMap<Nibbles, RevealedNode>, SparseTrieError> {
+        let mut result = HashMap::with_capacity_and_hasher(paths.len(), Default::default());
+        for path in paths {
+            if let Some(node) = self.trie_node(path)? {
+                result.insert(path.clone(), node);
+            }
+        }
+        Ok(result)
+    }
 }
 
 /// Default trie node provider factory that creates [`DefaultTrieNodeProviderFactory`].

crates/trie/sparse/src/trie.rs

@@ -1417,7 +1417,7 @@ impl SerialSparseTrie {
         while let Some((mut path, level)) = paths.pop() {
             match self.nodes.get(&path).unwrap() {
                 SparseNode::Empty | SparseNode::Hash(_) => {}
-                SparseNode::Leaf { key: _, hash } => {
+                SparseNode::Leaf { key: _, hash, .. } => {
                     if hash.is_some() && !prefix_set.contains(&path) {
                         continue
                     }
@@ -1438,7 +1438,7 @@ impl SerialSparseTrie {
                         paths.push((path, level + 1));
                     }
                 }
-                SparseNode::Branch { state_mask, hash, store_in_db_trie: _ } => {
+                SparseNode::Branch { state_mask, hash, .. } => {
                     if hash.is_some() && !prefix_set.contains(&path) {
                         continue
                     }